locking ring, stamped part with multiple locking rings and solenoid valve with locking ring

Abstract

A retaining clamping ring (22) for axially holding a cylindrical body at its circumferential surface, with an axial fictitious central axis, a circumferentially closed annular central part (24) circulating around the central axis, from the inner edge of which at least one inner retaining tooth (26) projects radially inwards and from the outer edge of which outer retaining teeth (28) project radially outwards, wherein the at least one inner retaining tooth (26) projects obliquely inwards to a plane (B) perpendicular to the central axis and simultaneously away from the annular central part (24) and wherein at least some of the outer retaining teeth (28) also project obliquely outwards to a plane (B) perpendicular to the central axis (A) and simultaneously away from the annular central part (24).

Description

The invention relates to a locking clamping ring for axially holding a cylindrical body on its circumferential surface. The invention further relates to a stamped part in the form of a one-piece sheet metal part for the production of several such locking clamping rings and to a solenoid valve actuator with such a locking clamping ring. Such locking clamping rings are used, among other things, in solenoid valve actuators where a core guide tube must be held axially in an outer housing and where tolerance compensation due to thermal expansion is required. These retaining rings have several retaining teeth on their inner edge that yield elastically when pushed onto an axle or cylindrical part. The retaining teeth clamp onto, or may even cut into, the surface of the part to be held, creating an axial preload, as the retaining ring is supported against another part, particularly a housing, at its outer edge. However, if the part being held expands significantly due to thermal expansion, it can expand axially to a considerable extent, causing the retaining ring to become separated from the other part against which its outer edge normally rests, resulting in a loss of contact. This eliminates the axial preload, and the held part becomes movable. The object of the invention is therefore to create a retaining clamping ring that can compensate for larger thermal expansions. Furthermore, the manufacture of such retaining clamping rings is to be made more economical. Finally, a solenoid valve is to be created in which the core guide tube is securely held axially even under varying temperatures. According to the invention, a retaining clamping ring for axially holding a cylindrical body at its circumferential surface comprises an axial fictitious central axis, an annular central part circumferentially closed around the central axis, from the inner edge of which at least one inner retaining tooth projects radially inwards, and from the outer edge of which outer retaining teeth project radially outwards, wherein the at least one inner retaining tooth projects obliquely inwards and simultaneously away from the annular central part relative to a plane perpendicular to the central axis, and wherein at least some of the outer retaining teeth also project obliquely outwards and simultaneously away from the annular central part relative to a plane perpendicular to the central axis. The retaining teeth projecting obliquely on both sides create a spring-like clamping effect that elastically compensates for thermally induced changes in length of the core guide tube and ensures permanent contact between the retaining clamping ring and the solenoid valve housing. According to one embodiment, the angle at which the at least one inner retaining tooth is positioned relative to the plane is different from the angle at which the obliquely extending outer retaining teeth are positioned relative to the plane. The angles are adapted to the function (clamping function and support function with spring action). To ensure an optimal compromise between sufficient holding force and the compliance required for tolerance compensation, the angles can range from 15° to 30°. According to one variant, there are several internal retaining teeth evenly distributed around the circumference, or a single internal retaining tooth. The even distribution of several internal retaining teeth ensures a centric and uniform clamping force around the circumference of the cylindrical body. Optionally, tabs extending outwards in the plane between adjacent, angled outer retaining teeth can protrude from the ring's central section. These tabs serve as connecting elements in series production and enable the manufacture of multiple retaining rings as a single, continuous stamped part. According to one embodiment, several internal retaining teeth are present, and each internal retaining tooth is oriented radially outward in a top view towards an outwardly extending flap. This orientation facilitates manufacturing as a stamped part and enables uniform force transmission into the annular center section. To distribute the holding and supporting forces more evenly around the circumference and to increase the reliability of the connection, at least six external retaining teeth and / or internal retaining teeth can be provided. According to one variant, the retaining teeth have a rectangular shape when viewed axially, preferably with rounded outer corners. The rectangular base shape maximizes the contact area, while rounded corners reduce stress concentrations in the material and increase the component's service life. Optionally, the retaining teeth each have a circumferential contact edge on their underside, which is sharply angled downwards. The sharp angle of the contact edge improves clamping or even cutting into the surfaces of the core guide tube and the end wall, thereby significantly increasing the holding force. According to one embodiment, the locking ring is a sheet metal part in the form of a stamped and bent component. The stamped and bent design enables cost-effective mass production while maintaining high dimensional accuracy and reproducibility. To increase the bending stiffness of the ring center section and to prevent undesirable deformation of the ring under operating loads, the ring center section can have a circumferential stiffening bead. According to the invention, a stamped part in the form of a one-piece sheet metal part is provided for the production of multiple retaining rings. It has two parallel strip sections, between which several retaining rings extend. Each retaining ring has at least two outer retaining teeth or two tabs extending radially outwards from the ring's central section between adjacent outer retaining teeth. This stamped part enables the simultaneous production of multiple retaining rings in a single manufacturing step, which significantly reduces production costs for high volumes. According to one variant, the retaining teeth of the stamped part are angled. Angled retaining teeth in the stamped part allow for the direct production of the functionally relevant geometry in a combined stamping and bending process. According to the invention, a solenoid valve actuator comprises a coil, a coil core extending within the coil, a core guide tube surrounding and axially guiding the coil core, and an outer housing surrounding the coil with an end wall from which the core guide tube projects. A retaining ring is slid onto the core guide tube, with which at least one inner retaining tooth is clamped in the outer circumferential surface of the core guide tube and rests against the outer end wall with the outer retaining teeth. The retaining ring is axially elastically deformed and preloads the core guide tube axially outward from the outer housing. The elastic preload of the retaining ring holds the core guide tube permanently and without play in its axial position, even under fluctuating temperatures and the associated changes in component length. To reliably prevent axial displacement of the locking clamping ring under high operating loads, the outer retaining teeth and at least one inner retaining tooth can press into the end wall or against the outer circumferential surface of the core guide tube with their circumferentially extending contact edges on their underside, thereby creating a positive locking component in the connection. Further features and advantages of the invention will become apparent from the following description and the following drawings, to which reference is made. The drawings show: Fig. 1 a longitudinal section through an upper part of a solenoid valve actuator according to the invention, Fig. 2 a perspective top view of the solenoid valve actuator according to Fig. 1, Fig. 3 a perspective bottom view of the retaining clamp ring according to the invention, Fig. 4 a perspective top view of the retaining clamp ring according to Fig. 3, Fig. 5 a side view of the retaining clamp ring according to the invention according to Fig. 3, Fig. 6 a top view of a stamped part according to the invention for creating several retaining clamp rings according to the invention, and Fig. 7 an alternative embodiment of the retaining clamp ring according to the invention. Figure 1 shows a solenoid valve actuator 10 with an outer housing 12, which has an end wall 14. Inside the outer housing 12, a coil 16 is arranged, by means of which a closing part of a valve is moved. The coil 16 surrounds a coil core 18, which can optionally be designed as an armature and which is housed in a core guide tube 20. The core guide tube 20 is in particular a deep-drawn part made from a thin sheet of metal. The core guide tube 20 extends through the end wall 14 and projects outwards. At its lower end, the core guide tube 20 is provided, for example, with an outwardly facing flange, with which it rests against a part, for example, the lower end face of the coil 16. The core guide tube 20 must be mounted axially without play in the outer housing 12. For this purpose, a locking clamping ring 22 is provided, which is clamped to the end of the core guide tube 20 that projects outwards opposite the end wall 14 and which bears against the end wall 14. The core guide tube 20 is axially pre-tensioned upwards by means of the locking clamping ring 22, which is axially spring-elastic; that is, the locking clamping ring 22 is supported on its radial outer circumference against the end wall 14 and clamps radially on the inside of the core guide tube 20. Fig. 2 shows details of the locking clamp ring 22, which has an annular, circumferentially closed ring center part 24 that runs around a central axis A and which also forms the central axis of the coil core 18. Several, in this case six, internal retaining teeth 26, evenly distributed around the circumference, project radially inwards from the inner edge of the annular central part 24. These internal retaining teeth 26 clamp the locking clamping ring 22 to the outer circumferential surface of the core guide tube 20. The locking clamping ring 22 is pushed onto the upper end of the core guide tube 20 from above, whereby the inner retaining teeth 26 bend elastically upwards and slide along the outer circumferential surface of the core guide tube 20 to an end position in which they then grip the core guide tube 20. On the outer edge of the ring middle part 24, several, here for example also six, radially outwardly projecting outer retaining teeth 28 are provided, which bear against the end wall 14 at their outer, circumferentially extending contact edge 30, see Fig. 3. Between each pair of adjacent outer retaining teeth 28, an outwardly projecting flap 32 is provided, integrally formed on the ring central part 24. As can be seen in the top view according to Fig. 4, the ring middle part 24 has a circumferential stiffening bead 34 formed by plastic deformation. The inner and outer retaining teeth 26, 28 are oriented obliquely to a plane B perpendicular to the central axis A (see Fig. 5). Figure 2 shows that the inner retaining teeth 26 are all the same and directed obliquely radially inwards and simultaneously upwards, whereas the outer retaining teeth 28 are directed obliquely outwards and downwards from the annular central part 24. The basic orientation with respect to the central axis A is therefore the same for the retaining teeth 26 and 28. The angle α that the outer retaining teeth 28 make with the plane B is preferably different and smaller than the angle β that the inner retaining teeth 26 make with the plane B. In particular, the angle α is preferably about 15° and the angle β about 30°. This ensures that the inner retaining teeth 26 clamp securely on the core guide tube 20 and that the outer retaining teeth 28 deflect axially sufficiently. This spring elasticity is important when temperature changes cause the core guide tube 20 to expand lengthwise. Even then, the core guide tube 20 remains axially free of play in the rest of the solenoid valve actuator. For better retention, the contact edges 30 of the outer retaining teeth 28 can be sharp-edged, as can the lower contact edges 38 (see Fig. 4) of the inner retaining teeth 26. The shape of the retaining teeth 26, 28 is rectangular in axial view, with rounded outer corners 36. The lobes 32 are not inclined to plane B, but run parallel to it. The locking clamping ring 22 is a bent stamped part, which is stamped from a sheet of metal. Fig. 6 shows a corresponding stamped part 40, which has numerous locking clamping rings 22. After punching, two parallel strip sections 44 are formed, which run in a strip shape and between which the numerous locking clamping rings 22 are positioned, the locking clamping rings 22 not yet being separated from the punched part in the state shown in Fig. 6. In this intermediate stage of the manufacturing process, the retaining rings 22 still hang over the flaps 32 and thin bridges 46 on the bands 44 and are held by them. The bridges 46 are then cut off, so that the retaining rings 22 are finally separated. The reshaping of the retaining teeth 26, 28 can be carried out in the state shown in Fig. 6. In the embodiment shown, the lobes 32 lie in a radial extension to the inner retaining teeth 26, but this is not necessarily the case. The lobes 32 can also serve to stabilize, especially during the elastic deformation of the retaining teeth 26, 28. The inner retaining teeth 26 can optionally cut into the outer circumferential surface of the core guide tube 20 with their contact edges 38; optionally the contact edges 30 can also cut into the end wall 14. As mentioned previously, during the assembly of the solenoid valve actuator, the retaining clamping ring 22 is pushed onto the core guide tube 20 from above, whereby the inner retaining teeth 26 deform elastically upwards and clamp onto the core guide tube 20. Subsequently, the outer retaining teeth 28 are deformed elastically and axially as soon as they contact the end wall 14. Instead of several internal retaining teeth 26, only one retaining tooth 26 can be provided, as shown in Fig. 7. This retaining tooth 26 clamps onto the outer circumferential surface. The clamping force on the outer circumferential surface is exerted between the retaining tooth 26 and the diametrically opposite inner edge of the ring center section 24.

Claims

A retaining clamping ring (22) for axially holding a cylindrical body at its circumferential surface, with an axial fictitious central axis, a circumferentially closed annular central part (24) circulating around the central axis, from the inner edge of which at least one inner retaining tooth (26) projects radially inwards and from the outer edge of which outer retaining teeth (28) project radially outwards, wherein the at least one inner retaining tooth (26) projects obliquely inwards to a plane (B) perpendicular to the central axis and simultaneously away from the annular central part (24) and wherein at least some of the outer retaining teeth (28) also project obliquely outwards to a plane (B) perpendicular to the central axis (A) and simultaneously away from the annular central part (24). A retaining clamping ring (22) according to claim 1, characterized in that the angle (α) in which the at least one inner retaining tooth (26) is located to the plane is not equal to the angle (β) in which the obliquely extending outer retaining teeth (28) are located to the plane (B). Safety clamping ring (22) according to claim 2 , characterized in that the angles (α, β) are in the range of 15° to 30°. A retaining clamping ring (22) according to one of the preceding claims, characterized in that several circumferentially uniformly distributed inner retaining teeth (26) or a singular inner retaining tooth (26) are present. A retaining clamping ring (22) according to one of the preceding claims, characterized in that between adjacent, obliquely extending outer retaining teeth (28) in the plane (B) outwardly extending lobes (32) protrude from the ring central part (24). A retaining clamping ring (22) according to claim 5, characterized in that several internal retaining teeth (26) are provided and each internal retaining tooth (26) is aligned in a top view in a radial direction outwards to an outwards extending flap (32). A retaining clamping ring (22) according to one of the preceding claims, characterized in that at least six outer retaining teeth (28) and / or inner retaining teeth (26) are provided. A retaining clamping ring (22) according to one of the preceding claims, characterized in that the retaining teeth (26, 28) have a rectangular shape when viewed axially, preferably with rounded outer corners. A retaining clamping ring (22) according to one of the preceding claims, characterized in that the retaining teeth (26, 28) each have a circumferentially extending contact edge (30) on their underside, which is formed with a sharp edge towards the bottom. A locking clamping ring (22) according to one of the preceding claims, characterized in that it is a sheet metal part in the form of a stamped and bent part. A locking clamping ring (22) according to one of the preceding claims, characterized in that the ring middle part (24) has a circumferential stiffening bead (34). Stamped part (40) in the form of a one-piece sheet metal part for the production of several locking clamping rings (22) according to one of the preceding claims, with two parallel strip sections (44) between which several locking clamping rings (22) extend, which each have at least two outer retaining teeth (28) or two flaps (32) extending radially outwards from the ring central part (24) between adjacent outer retaining teeth (28) and merge one-piece into the respective strip section (44). Stamped part (40) according to claim 12, characterized in that the retaining teeth (26, 28) are angled. Solenoid valve actuator (10) comprising a coil (16), a coil core (18) extending in the coil (16), a core guide tube (20) surrounding and axially guiding the coil core (18), and an outer housing (12) surrounding the coil (16) with an end wall (14) from which the core guide tube (20) protrudes, wherein a locking clamping ring (22) according to one of claims 1 to 11 is pushed onto the core guide tube (20), with which at least one inner retaining tooth (26) is clamped in the outer circumferential surface of the core guide tube (20) and rests on the outer end wall (14) with the outer retaining teeth (28), wherein the locking clamping ring (22) is axially elastically deformed and preloads the core guide tube (20) in the axial direction out of the outer housing (12). Solenoid valve actuator (10) according to claim 14, characterized in that the outer retaining teeth (28) and the at least one inner retaining tooth (26) with their circumferentially extending contact edges (30, 38) cut into the end wall (14) or into the outer circumferential surface of the core guide tube (20) on their underside.

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